A bridle, such as a curb bridle, makes it possible for the advanced rider to give finer assistance to a suitably trained horse. In the bridle of trained dressage horses, the curb bit usually consists of two bits so that the rider needs to handle two pairs of reins at the same time. The chin chains usually used today, for example, in a curb bridle, consist of a plurality of oval rings which taper towards the ends and nestle into one another. A small, round ring located at the centre of the chin chain, called a lip strap ring, was historically used to buckle on the so-called lip strap which was intended to prevent any slippage if a chin chain was not of suitable length (this is almost of no importance today). The chin chain which is always to be turned out to the right is suspended in the adjacent chin chain hooks from above and specifically from inside on the right side and from outside on the left side. Its correct bending or flexibility has a substantial influence on a good bridle and action.
The chin chains usually used today for curb bits have the disadvantage that the members twist easily so that individual members are positioned upright and press onto the lips of the horse if they have not been turned outwards very carefully each time before putting on.
The German Federal Patent 361479 discloses a chin chain for curb bits where each member is provided with an eye through which the neighbouring member can be inserted so that the members cannot twist. In addition, this patent specification discloses the design of chin chain such that every two neighbouring members are rigidly connected one to the other instead of in an articulated fashion.
Chin chains consisting only of members or chain elements which can be turned out to the right, i.e., chin chains whose linkage of the individual members is in the same direction over the entire length of the chain, effect a nonuniform pull on the two sides of the curb bit and the pull has the effect that the linkage of the individual members acting in the same direction has a lever effect on the chin chain hooks located to the right and left of the horse's mouth with the effect that in general the left chin chain hook is pulled away from the mouth and the right chin chain hook is pulled towards the mouth As a result of this different action of forces on the two hooks or corners of the mouth (outward on the left, inward on the right), on the one hand a different lever effect is achieved on the curb bit in the horse's mouth More pressure is exerted on the tooth float blade and on the lip on the right than on the left. At the same time, attention should be paid to the effects on the horse's mouth or the corner of the mouth which are produced by the pull inward onto the right chin chain hook. This can frequently be observed as a lip which droops on one side on the right side of the horse's mouth. In addition, this frequently results in injuries to the corner of the mouth as far as tongue defects, such as a pushing out of the tongue for example.